昆明地铁重叠隧道盾构施工位移数值模拟分析

昆明地铁首期工程一号线临近昆明火车站区间采用近距离重叠隧道方案通过,其上下垂直净距仅1.8~4.0 m,盾构施工期间的地表位移对既有建筑物的正常使用将会造成影响,是地铁施工中应重点控制的关键。因此,运用PLAXIS数值软件,对设计盾构方案施工条件下的地表沉降及上下隧道关键部位的位移,进行数值模拟,以评估设计方案的可行性。对上下隧道的洞顶、洞底及隧道中心线所对应地表的位移进行了数值模拟与监测的对比分析。结果表明:在既有设计方案条件下,各处位移均小于昆明地铁监测项目控制值,可以采用设计方案中的盾构参数进行施工。

Analysis on Numerical Simulation for Shield Construction Displacement of Overlapped Tunnels of Kunming Metro

The Phase I project of Kunming Metro Line 1 is adjacent to Kunming Railway Station, where passes in design is two short distance overlapped tunnels with the vertical net distance of 1. 8 m~4. 0 m. The ground surface subsidence during the shield construction of metro may cause significant impact on the normal use of the existing buildings. This is the key point to be controlled during construction of tunnels. Therefore, in this paper, the numerical software PLAXIS is adopted to simulate the ground surface subsidence, as well as other key points’ displacement under the designed shield construction method so as to evaluate the feasibility of design scheme. The displacements of the tunnel roofs and bottoms of the lower and upper tunnels and the ground surface subsidence are simulated and monitored and comparative analysis is made. Results show that all the displacements are smaller than the controlled value of Kunming Metro in the existing design scheme, so the shield parameters in the design scheme can be taken as a reference for similar projects.